Situation #1 winner:
Maneuverability: Draw. The three tread design while odd looking gives the C&C Scorpion great maneuverability for a tank. However, the C&C Tank has to be facing it's opponent due to the fact that it's cannon is fixed forward. Whereas the Halo Tank's gun can rotate 360 degrees.
Firepower: C&C Scorpion. The Halo Scorpion has a 90mm cannon while the C&C tank has a 150mm cannon.
Armor: While both are reasonably armored, the C&C Tank has much more armor that the Halo Tank. However, the C&C's armor design, while greatly armoring the front of the tank, leaves the back almost completely exposed. But it's maneuverability makes up for it a little.
Winner: This is a tough one to call but, I'd have to say that the... C&C Scorpion Tank takes this. Unless the Halo Scorpion comes up behind the C&C Tank inside the city, then it is a screwed tank. The C&C Tank's armor and maneuverability together give it the win here.
Situation #2 winner: Same. The upgrades for the C&C Scorpion make it all the easier for it to take the win. The only downfall being that the new laser cannon would slightly hinder it's maneuverability.
Until next time, Hasta La Vista Baby!